1. Field of the Invention
The present invention relates to an internal combustion engine blowby gas crankcase emission control system mounted in a vehicle such as a motorcycle or a four-wheel vehicle.
2. Description of Background Art
To prevent blowby gas that leaks out from a combustion chamber into a crankcase from being emitted into the air, a crankcase emission control system is configured so that blowby gas is returned to the intake side and is again fed to the combustion chamber from there. In addition, a combustion process is applied and provided to an engine which is a representative example of an internal combustion engine. The crankcase emission control system is known that includes a configuration wherein a crankcase and an intake manifold are connected and a cylinder head cover (the inside) is in communication with the crankcase and an air cleaner are connected. See for example, JP-A-61-198512.
However, in a conventional type crankcase emission control system, as blowby gas in a crankcase and in a cylinder head cover is returned to the intake side (an intake manifold and an air cleaner) by using mutually independent paths, a sufficient gas-liquid separation function is required to be provided to the respective paths. More specifically, a large-size gas-liquid separator is required so as to prevent an oil component that is unseparated from blowby gas from being returned to the intake side. Thus, a breather having a large capacity is required to be provided to the cylinder head side or an intricate labyrinth structure is required to be formed with a large-sizing of a cylinder head, that is, an engine (an internal combustion engine). This results in an increase in the manufacturing cost.